Himawari-8 (left) and MTSAT-2 (right) water vapor channel images [click to play animation]

Now that Himawari-8 is their operational geostationary satellite, the Japanese Meteorological Agency (JMA) decommissioned MTSAT-1R (which was relaying the direct broadcast of MTSAT-2 imagery) as of 0630 UTC on 04 December 2015. A comparison of the final 5 hours of available MTSAT-2 6.75 µm water vapor channel images with the coresponding 6.2 µm water vapor channel images from Himawari-8 (above) demonstrated the advantages of improvements in both spatial resolution (2-km with Himawari, vs 4-km with MTSAT) and temproal resolution (10-minute with Himawari, vs 30-minute with MTSAT) for resolving the signature of middle-tropospheric waves within a dry slot in the wake of an occluded storm-force low over the North Pacific Ocean (surface analyses).

In addition, there are 3 water vapor channels on the Himawari-8 AHI instrument – a comparison of these 3 water vapor bands (below) offers a closer look at the aforementioned waves within the dry slot. The weighting functions for each of the 3 water vapor bands (centred at 6.2 µm, 6.9 µm, and 7.3 µm) peak at progressivesly lower altitudes, providing different views of features within those particular atmospheric layers. The same color enhancement is applied to the 3 sets of water vapor images — note that warmer brightness temperatures (yellow to orange colors) dominate the 6.9 µm and 7.3 µm images (which are showing features at lower altitudes, where the atmosphere is warmer).

Similar improvements in spatial and temporal resolution will be seen with imagery from the upcoming GOES-RABI, which will also feature 3 similar water vapor bands (weighting functions); however, the ABI will provide full-disk images every 5 minutes.